U.S. patent application number 11/486569 was filed with the patent office on 2007-03-15 for method of manufacturing quad flat non-leaded semiconductor package.
This patent application is currently assigned to Siliconware Precision Industries Co., Ltd.. Invention is credited to Chien-Ping Huang, Chun-Yuan Li, Fu-Di Tang.
Application Number | 20070059863 11/486569 |
Document ID | / |
Family ID | 37855710 |
Filed Date | 2007-03-15 |
United States Patent
Application |
20070059863 |
Kind Code |
A1 |
Li; Chun-Yuan ; et
al. |
March 15, 2007 |
Method of manufacturing quad flat non-leaded semiconductor
package
Abstract
A method of manufacturing a quad flat non-leaded semiconductor
package is provided. A metal plate is prepared and is defined with
predetermined positions of a plurality of electrically conductive
pads. A resist layer is formed on the metal plate, and a plurality
of openings are formed in the resist layer and correspond to the
predetermined positions of the electrically conductive pads. A
solderable metal plated layer is formed in each of the openings of
the resist layer. The resist layer on the metal plate is removed. A
portion of the metal plate, which is not covered by the metal
plated layers, is etched using the metal plated layers as a mask. A
chip is mounted on the metal plate and is electrically connected to
the electrically conductive pads. A molding process is performed
such that the chip and the metal plate are encapsulated by an
encapsulant.
Inventors: |
Li; Chun-Yuan; (Taichung
Hsien, TW) ; Tang; Fu-Di; (Taichung Hsien, TW)
; Huang; Chien-Ping; (Hsinchu Hsein, TW) |
Correspondence
Address: |
EDWARDS & ANGELL, LLP
P.O. BOX 55874
BOSTON
MA
02205
US
|
Assignee: |
Siliconware Precision Industries
Co., Ltd.
Taichung
TW
|
Family ID: |
37855710 |
Appl. No.: |
11/486569 |
Filed: |
July 14, 2006 |
Current U.S.
Class: |
438/113 ;
257/E23.054 |
Current CPC
Class: |
H01L 2224/48091
20130101; H01L 2224/16 20130101; H01L 2924/01078 20130101; H01L
2224/48247 20130101; H01L 2224/16245 20130101; H01L 2924/01028
20130101; H01L 24/45 20130101; H01L 2924/00014 20130101; H01L
2924/00014 20130101; H01L 2924/00012 20130101; H01L 21/4832
20130101; H01L 2924/181 20130101; H01L 24/48 20130101; H01L
2224/45144 20130101; H01L 2924/01079 20130101; H01L 2224/48091
20130101; H01L 2224/45144 20130101; H01L 2924/181 20130101; H01L
23/49582 20130101; H01L 2924/01046 20130101 |
Class at
Publication: |
438/113 |
International
Class: |
H01L 21/00 20060101
H01L021/00 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 15, 2005 |
TW |
094131778 |
Claims
1. A method of manufacturing a quad flat non-leaded semiconductor
package, comprising the steps of: preparing a metal plate having a
first surface and an opposed second surface, wherein the first
surface of the metal plate is defined with predetermined positions
of a plurality of electrically conductive pads; forming a resist
layer on each of the first and second surfaces of the metal plate;
forming a plurality of openings in the resist layers on the first
and second surfaces of the metal plate, the openings corresponding
to the predetermined positions of the electrically conductive pads;
forming a metal plated layer in each of the openings of the resist
layers on the first and second surfaces of the metal plate;
removing the resist layer on the first surface of the metal plate;
performing an etching process on the first surface of the metal
plate, such that a portion of the metal plate, which is not covered
by the metal plated layers, is etched; removing the resist layer on
the second surface of the metal plate; mounting a chip on the first
surface of the metal plate and electrically connecting the chip to
the electrically conductive pads; performing a molding process to
form an encapsulant for encapsulating the chip and the first
surface of the metal plate; etching the second surface of the metal
plate to separate the electrically conductive pads from each other;
and performing a singulation process such that the quad flat
non-leaded semiconductor package is obtained.
2. The method of claim 1, wherein the chip is electrically
connected to the electrically conductive pads by one of bonding
wires and conductive bumps.
3. The method of claim 1, wherein the metal plated layers are
formed on the predetermined positions of the electrically
conductive pads.
4. The method of claim 1, wherein the metal plate is further
defined with a position of a die pad for mounting the chip
thereon.
5. The method of claim 4, wherein the metal plate is further formed
with a metal plated layer on the position of the die pad.
6. The method of claim 4, wherein the positions of the electrically
conductive pads are located around the position of the die pad.
7. The method of claim 4, wherein the resist layers are further
formed with openings corresponding to the position of the die
pad.
8. The method of claim 4, wherein the metal plate is further
defined with a position of a ground ring.
9. The method of claim 8, wherein the position of the ground ring
is located around the position of the die pad.
10. The method of claim 9, wherein the electrically conductive pads
are located around the ground ring.
11. The method of claim 1, wherein the metal plate is made of
copper.
12. The method of claim 1, wherein the electrically conductive pads
are arranged in a single row.
13. The method of claim 1, wherein the electrically conductive pads
are arranged in multiple rows.
14. The method of claim 1, wherein the resist layer is a
photoresist layer.
15. The method of claim 1, wherein the openings of the resist
layers are formed by exposure, development and etching.
16. The method of claim 1, wherein the metal plated layer has at
least four layers including gold/palladium/nickel/palladium
(Au/Pd/Ni/Pd) layers.
17. The method of claim 1, wherein the metal plated layers on the
first surface of the metal plate serve as a mask during etching the
first surface of the metal plate.
18. The method of claim 1, wherein the encapsulant is made of a
resin material.
19. The method of claim 1, wherein the second surface of the metal
plate is exposed from the encapsulant.
20. The method of claim 1, wherein the metal plated layers on the
second surface of the metal plate serve as a mask during etching
the second surface of the metal plate.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to methods of manufacturing
quad flat non-leaded semiconductor packages, and more particularly,
to a method of manufacturing a quad flat non-leaded semiconductor
package without performing an electroless plating process and a
lithography process after a molding process.
BACKGROUND OF THE INVENTION
[0002] Quad flat non-leaded semiconductor package as shown in FIG.
1 comprises a chip 51 mounted on a die pad 50 of a non-leaded lead
frame, wherein the chip 51 is electrically connected to a plurality
of electrically conductive pads 53 around the die pad 50 through
bonding wires 52. The electrically conductive pads 53 in place of
conventional leads are used to transmit signals from the chip 51 to
an external device. Compared with a typical lead-frame-based
semiconductor package using leads for signal transmission, the quad
flat non-leaded semiconductor package avoids the need of bending
the lead frame and thus has a reduced height, making the quad flat
non-leaded semiconductor package widely employed in electronic
products.
[0003] The quad flat non-leaded semiconductor package can be
fabricated by a method as disclosed in U.S. Pat. No. 6,498,099. As
shown in FIG. 2A, a copper plate 60 is firstly prepared. Then, as
shown in FIG. 2B, an upper surface and a lower surface of the
copper plate 60 are partially etched to define predetermined
positions of a die pad 61 and a plurality of electrically
conductive pads 62, and a nickel/palladium (Ni/Pd) layer (not
shown) is plated on the copper plate 60. As shown in FIG. 2C, a
chip 65 is mounted on the die pad 61 and is electrically connected
to the electrically conductive pads 62 via bonding wires 66. As
shown in FIG. 2D, a molding process is performed to form an
encapsulant 67 for protecting the chip 65 and the bonding wires 66.
As shown in FIG. 2E, a bottom surface of the copper plate 60, which
is exposed from the encapsulant 67, is coated with a photoresist
layer 68, wherein the photoresist layer 68 can be a dry film or a
liquid film. By using the photoresist layer 68 as a mask, an
etching process is performed on the copper plate 60 to separate the
die pad 61 and the plurality of electrically conductive pads 62
from each other, as shown in FIG. 2F. After removing the
photoresist layer 68, an electroless plating process is performed
to form a solderable gold (Au) plated layer (not shown) on the
copper plate 60, and a singulation process is carried out such that
the quad flat non-leaded semiconductor package is obtained, as
shown in FIG. 2G.
[0004] However, the above fabrication method including coating the
photoresist layer 68 on the copper plate 60 and performing
exposure, development and etching after the molding process, causes
significant drawbacks. Firstly, performing a lithography process
after the molding process does not allow the photoresist layer 68
to be directly applied over the entire panel-shaped copper plate
but needs to apply the photoresist layer 68 on a strip-shaped
copper plate, thereby increasing the difficulty and cost of the
fabrication processes. Further, the copper plate 60 may become
warped by the molding process performed in a high temperature,
making the photoresist layer 68 difficult to be coated flatly on
the copper plate 60. Moreover, the gold plated layer formed by
electroless plating does not have strong adhesion to the copper
plate 60, thereby resulting in poor solderability. These drawbacks
lead to a low product yield and increased fabrication cost for the
above quad flat non-leaded semiconductor package.
[0005] Therefore, the problem to be solved here is to provide a
method of manufacturing a quad flat non-leaded semiconductor
package, which can overcome the above drawbacks to increase the
product yield and reduce the fabrication cost of the semiconductor
package.
SUMMARY OF THE INVENTION
[0006] In light of the foregoing drawbacks of the prior art, an
objective of the present invention is to provide a method of
manufacturing a quad flat non-leaded semiconductor package without
performing a lithography process after a molding process.
[0007] Another objective of the present invention is to provide a
method of manufacturing a quad flat non-leaded semiconductor
package, which only needs to perform an etching process after a
molding process.
[0008] Still another objective of the present invention is to
provide a method of manufacturing a quad flat non-leaded
semiconductor package with low cost.
[0009] A further objective of the present invention is to provide a
method of manufacturing a quad flat non-leaded semiconductor
package with a plated layer having better solderability.
[0010] To achieve the above and other objectives, the present
invention proposes a method of manufacturing a quad flat non-leaded
semiconductor package, comprising the steps of: preparing a metal
plate having a first surface and an opposed second surface, wherein
the first surface of the metal plate is defined with predetermined
positions of a die pad and a plurality of electrically conductive
pads; forming a resist layer on each of the first and second
surfaces of the metal plate; forming a plurality of openings in the
resist layers on the first and second surfaces of the metal plate,
the openings corresponding to the predetermined positions of the
die pad and the electrically conductive pads; forming a solderable
metal plated layer in each of the openings of the resist layers;
removing the resist layer on the first surface of the metal plate;
performing an etching process on the first surface of the metal
plate, such that a portion of the metal plate, which is not covered
by the metal plated layers, is etched; removing the resist layer on
the second surface of the metal plate; mounting a chip to the die
pad on the first surface of the metal plate; electrically
connecting the chip to the electrically conductive pads via a
plurality of bonding wires; performing a molding process to form an
encapsulant for encapsulating the chip, the bonding wires and the
first surface of the metal plate; etching the second surface of the
metal plate with the metal plated layers serving as a mask, so as
to separate the die pad and the electrically conductive pads from
each other; and performing a singulation process such that the quad
flat non-leaded semiconductor package is obtained. Further, besides
the electrically conductive pads, a ground ring can also be formed
around the die pad, so as to provide both a grounding effect and
signal transmission for the chip.
[0011] According to another embodiment of the present invention, a
method of manufacturing a quad flat non-leaded semiconductor
package comprises the steps of: preparing a metal plate having a
first surface and an opposed second surface, wherein the first
surface of the metal plate is defined with predetermined positions
of a plurality of electrically conductive pads; forming a resist
layer on each of the first and second surfaces of the metal plate;
forming a plurality of openings in the resist layers on the first
and second surfaces of the metal plate, the openings corresponding
to the predetermined positions of the electrically conductive pads;
forming a metal plated layer in each of the openings of the resist
layers; removing the resist layer on the first surface of the metal
plate; performing an etching process on the first surface of the
metal plate, such that a portion of the metal plate, which is not
covered by the metal plated layers, is etched; removing the resist
layer on the second surface of the metal plate; mounting a flip
chip on the first surface of the metal plate and electrically
connecting the chip to the electrically conductive pads via a
plurality of conductive bumps; performing a molding process to form
an encapsulant for encapsulating the chip, the conductive bumps and
the first surface of the metal plate; etching the second surface of
the metal plate to separate the electrically conductive pads from
each other; and performing a singulation process such that the quad
flat non-leaded semiconductor package is obtained.
[0012] The resist layer can be a dry film. As the openings of the
resist layers correspond to the predetermined positions of the die
pad and the plurality of electrically conductive pads, the metal
plated layers formed in the openings are applied on the
predetermined positions of the die pad and the electrically
conductive pads.
[0013] The metal plated layer has at least four layers preferably
including gold/palladium/nickel/palladium (Au/Pd/Ni/Pd) layers.
Also, the metal plated layers on the first and second surfaces of
the metal plate serve as a mask when etching the first surface and
the second surface of the metal plate.
[0014] Therefore, the method of the present invention allows a
plating process of forming the metal plated layers and a
lithography process to be completed on a panel-shaped metal plate,
instead of a strip-shaped metal plate, before the molding process.
That is, after defining the die pad and the electrically conductive
pads, the fabrication processes such as die bonding, forming
electrical connection and molding are performed, and then only a
simple etching step is needed after the molding process to
fabricate the quad flat non-leaded semiconductor package. Thus, the
present invention has reduced difficulty and cost of the
fabrication processes as not requiring the electroless plating and
lithography processes in the prior art after the molding process,
and the present invention also improves the product yield of the
quad flat non-leaded semiconductor package and provides a metal
plated layer having better solderability, such that the drawbacks
in the prior art are solved.
BRIEF DESCRIPTION OF DRAWINGS
[0015] The present invention can be more fully understood by
reading the following detailed description of the preferred
embodiments, with reference made to the accompanying drawings,
wherein:
[0016] FIG. 1 (PRIOR ART) is a cross-sectional view of a
conventional quad flat non-leaded semiconductor package;
[0017] FIGS. 2A to 2G (PRIOR ART) are schematic cross-sectional
diagrams showing steps of a method of manufacturing a quad flat
non-leaded semiconductor package as disclosed in U.S. Pat. No.
6,498,099;
[0018] FIGS. 3A to 3I are schematic cross-sectional diagrams
showing steps of a method of manufacturing a quad flat non-leaded
semiconductor package according to a first embodiment of the
present invention;
[0019] FIGS. 4A to 4C are schematic diagrams showing a quad flat
non-leaded semiconductor package according to a second embodiment
of the present invention;
[0020] FIGS. 5A and 5B are schematic diagrams showing a quad flat
non-leaded semiconductor package according to a third embodiment of
the present invention; and
[0021] FIGS. 6A to 6I are schematic cross-sectional diagrams
showing steps of a method of manufacturing a quad flat non-leaded
semiconductor package according to a fourth embodiment of the
present invention.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0022] Preferred embodiments of a method of manufacturing a quad
flat non-leaded semiconductor package as proposed in the present
invention are described as follows with reference to FIGS. 3 to 6.
It should be understood that the drawings are schematic diagrams
only showing the relevant component for the present invention, and
the component layout could be more complicated in practical
implementation.
[0023] FIGS. 3A to 3I show steps of a method of manufacturing a
quad flat non-leaded semiconductor package according to a first
embodiment of the present invention. As shown in FIG. 3A, a metal
plate 10 made of such as copper is firstly prepared. The metal
plate 10 has a first surface 101 and an opposed second surface 102.
As the first surface 101 of the metal plate 10 serves as a
die-bonding surface, it is defined with predetermined positions of
a die pad 11 and a plurality of electrically conductive pads 12,
wherein the positions of the electrically conductive pads 12 are
located around the position of the die pad 11.
[0024] A resist layer 15 such as a dry film is formed on each of
the first and second surfaces 101, 102 of the metal plate 10, and
serves as a photoresist layer for use in subsequent exposure,
development and etching processes. As shown in FIG. 3B, a plurality
of openings 16 are formed in the resist layers 15 on the first and
second surfaces 101, 102 of the metal plate 10 by the exposure,
development and etching processes and correspond to the
predetermined positions of the die pad 11 and the electrically
conductive pads 12. Then, a metal plated layer 20 is formed in each
of the openings 16 of the resist layers 15 by plating. The metal
plated layer 20 has at least four layers preferably including
gold/palladium/nickel/palladium (Au/Pd/Ni/Pd) layers. Then, the
resist layer 15 on the first surface 101 of the metal plate 10 is
removed, such that only the metal plated layers 20 are left on the
first surface 101 of the metal plate 10, as shown in FIG. 3C.
[0025] As shown in FIG. 3D, an etching process is performed on the
first surface 101 of the metal plate 10, wherein the metal plated
layers 20 on the first surface 101 of the metal plate 10 are used
as a mask, and a portion of the metal plate 10, which is not
covered by the metal plated layers 20, is etched downwardly.
Subsequently, as shown in FIG. 3E, the resist layer 15 on the
second surface 102 of the metal plate 10 is removed. As a result,
the strip-shaped metal plate 10 having the die pad 11 and the
electrically conductive pads 12 is obtained.
[0026] As shown in FIG. 3F, a chip 30 is mounted to the position of
the die pad 11 on the first surface 101 of the metal plate 10,
wherein the position of the die pad 11 is formed with the metal
plated layer 20 thereon. Then, a wire-bonding process is performed
to electrically connect the chip 30 to the corresponding
electrically conductive pads 12 through bonding wires 31 such as
gold wires, wherein the positions of the electrically conductive
pads 12 are formed with the metal plated layers 20 thereon. As
shown in FIG. 3G, a molding process is performed such that the chip
30, the bonding wires 31 and the first surface 101 of the metal
plate 10 are encapsulated by an encapsulant 40 made of such as a
resin material. Both the second surface 102 of the metal plate 10
and the metal plated layers 20 on the second surface 102 of the
metal plate 10 are exposed from the encapsulant 40.
[0027] After the molding process, since the die pad 11 and the
plurality of electrically conductive pads 12 are still connected to
each other, an etching process is performed directly on the second
surface 102 of the metal plate 10 by using the metal plated layers
20 on the second surface 102 of the metal plate 10 as a mask, such
that a portion of the copper plate 10, which is located between the
die pad 11 and the plurality of electrically conductive pads 12, is
completely etched away, making the die pad 11 and the electrically
conductive pads 12 separated from each other, as shown in FIG. 3H.
Finally, as shown in FIG. 3I, a singulation process is carried out
to cut the encapsulant 40 and the copper plate 10 along peripheral
portions of the electrically conductive pads 12, such that the quad
flat non-leaded semiconductor package is obtained.
[0028] It should be noted that the arrangement of the electrically
conductive pads is not limited to a single row of the electrically
conductive pads 12 around the die pad 11 as described in the above
first embodiment, but may also be multiple rows of electrically
conductive pads as shown in FIGS. 4A, 4B and 4C according to a
second embodiment of the present invention. As shown in FIG. 4A,
the metal pad 10 is formed with the die pad 11, an inner row of
electrically conductive pads 121 and an outer row of electrically
conductive pads 122. After die-bonding, wire-bonding and molding
processes are completed, an etching process is performed to
separate the die pad 11, the inner row of electrically conductive
pads 121 and the outer row of electrically conductive pads 122 from
each other, as shown in a cross-sectional view of FIG. 4B and a
bottom view of FIG. 4C.
[0029] FIGS. 5A and 5B are respectively a cross-sectional view and
a bottom view of a quad flat non-leaded semiconductor package
according to a third embodiment of the present invention. The
semiconductor package of the third embodiment is similar to that of
the above embodiments, with a primary difference in that in the
third embodiment, the metal plate is further defined with a
position of a ground ring besides the positions of the die pad and
the electrically conductive pads. As shown in FIGS. 5A and 5B, a
ring-shaped structure such as a ground ring 123 is formed around
the die pad 11 and a plurality of electrically conductive pads 124
are formed around the ground ring 123. When the chip 30 is mounted
to the die pad 11, it can be electrically connected to both the
ground ring 123 and the electrically conductive pads 124 by the
bonding wires 31, thereby providing the chip 30 with grounding and
signal transmission functions. In the foregoing embodiments, the
chip 30 is electrically connected to the electrically conductive
pads 12 via the bonding wires 31, which however does not set a
limitation to the present invention. FIGS. 6A to 6I show steps of a
method of manufacturing a quad flat non-leaded semiconductor
package according to a fourth embodiment, wherein the chip 30 is
electrically connected to the metal plate 10 through a flip-chip
process. As shown in FIG. 6A, a metal plate 10 is firstly prepared,
which has a first surface 101 and an opposed second surface 102,
wherein the first surface 101 of the metal plate 10 is defined with
predetermined positions of a plurality of electrically conductive
pads 12. A resist layer 15 is formed on each of the first and
second surfaces 101, 102 of the metal plate 10. Then, as shown in
FIG. 6B, a plurality of openings 16 are formed in the resist layers
15 and correspond to the predetermined positions of the
electrically conductive pads 12. Then, as shown in FIG. 6C, a metal
plated layer 20 is formed in each of the openings 16 of the resist
layers 15 by plating. As shown in FIG. 6D, the resist layer 15 on
the first surface 101 of the metal plate 10 is removed. An etching
process is performed on the first surface 101 of the metal plate
10, such that a portion of the metal plate 10, which is not covered
by the metal plated layers 20, is etched. Subsequently, as shown in
FIG. 6E, the resist layer 15 on the second surface 102 of the metal
plate 10 is removed. As shown in FIG. 6F, a chip 30 is mounted to
the first surface 101 of the metal plate 10 in a flip-chip manner
such that the chip 30 is electrically connected to the
corresponding electrically conductive pads 12 through a plurality
of conductive bumps 50.
[0030] Then, as shown in FIG. 6G, a molding process is performed
such that the chip 30, the conductive bumps 50 and the first
surface 101 of the metal plate 10 are encapsulated by an
encapsulant 40. Moreover, as shown in FIG. 6H, an etching process
is performed on the second surface 102 of the metal plate 10 so as
to separate the electrically conductive pads 12 from each other.
Finally, as shown in FIG. 6I, a singulation process is carried out
to obtain the quad flat non-leaded semiconductor package according
to the fourth embodiment of the present invention.
[0031] Therefore, the method of the present invention allows the
plating process of forming the metal plated layers and a
lithography process to be completed on a panel-shaped metal plate,
instead of a strip-shaped metal plate, before the molding process.
That is, after defining the die pad and the electrically conductive
pads, the fabrication processes such as die bonding, forming
electrical connection and molding are performed, and then only a
simple etching step is needed after the molding process to
fabricate the quad flat non-leaded semiconductor package. Thus, the
present invention has reduced difficulty and cost of the
fabrication processes as not requiring the electroless plating and
lithography processes in the prior art after the molding process,
and the present invention also improves the product yield of the
quad flat non-leaded semiconductor package and provides a metal
plated layer having better solderability.
[0032] The invention has been described using exemplary preferred
embodiments. However, it is to be understood that the scope of the
invention is not limited to the disclosed embodiments. On the
contrary, it is intended to cover various modifications and similar
arrangements. The scope of the claims, therefore, should be
accorded the broadest interpretation so as to encompass all such
modifications and similar arrangements.
* * * * *